Institute or Biogeochemistry and Marine Chemistry
at the Center or Marine Research and Climatology, University or
Hamburg, Hamburg, FRG.

A. Background

Aside from helium, living and cosmic matter arc principally composed
of the same chemical elements, hydrogen oxygen-carbon-nitrogen,
reading in order of abundance, as: C -O -H- N vs H -O- C- N. In
contrast, the Earth has an entirely different bulk composition iron-oxygen-silicon-magnesium.
In comparing the various patterns one might suggest that living
matter sprouts directly out of the ancestral universal matrix, whereas
terrestrial matter must be a late derivation product of that matrix.
Only oxygen ranks high in all three compartments: cosmos, life,
and earth. Thus, it is tempting to look for the roots of life in
outer space. Actually, such an attempt is in strong contrast to
textbook dogma where the origin of life presupposes a synthesis
of vital monomers in a reducing terrestrial atmosphere by means
of high energy radiation. A subsequent "raining out" is assumed
to have led to a "primordial organic soup" from which physiologically
interesting polymers and eventually the first living cell arose
(Oparin 1953). To prime the pump of my antithesis, a few details
on the distribution of matter in interstellar space and its fractionation
in the course of solar and planetary evolution are needed. Its further
assemblage in the direction of a workable cellular system by way
of mineral templates and globular aggregates will represent the
essence of my subsequent presentation.

B. On Matter in Dark Molecular Clouds

Our galaxy, the Milky Way, would look if seen from the outside
somewhat like a galaxy in Ursa Major, M81, just 9 million light
years away from us (Fig. 1). About lOO billion stars are contained
in this magnificent spiral about 100000 light years across, and
quite a few may have planets like the Sun. Our solar system would
occupy a place close to the medium plain of the spiral about one
third the distance of the total diameter removed from the galactic
center. We need roughly 250 million Earth years to circumnavigate
the galactic center, Accordingly, this period of time has been defined
as 1 cosmic year. Of the mass we can account for in our galaxy,
about 95% resides in stars and the rest is interstellar gas and
dust in a ratio of about 99 to 1. However, this interstellar matter
is not uniformly distributed throughout the galaxy but is concentrated
in the form of clouds in regions close to the galactic plane of
symmetry, where new stars are born. To most of us, clouds are seen
more in conjunction with weather and climate. Namely, water vapor
will condense and form clouds of different sizes and shapes, which
are freely moving, can become dispersed or aggregate, and form a
cloud cover. Some regions are more cloudy than others. In due course,
they will rain out and the meteorological cycle will commence again
with the evaporation of water bodies. In analogy, interstellar clouds,
a few

Fig. I.Galaxy in Ursa Major, M81, about 9 million
light years away from us

light years or more in diameter, are in constant slow motion around
the galactic center. In their perpetual wandering through galactic
space, they may grow in size or collapse. During 1 cosmic year,
an average cloud could conceivably double its mass in sweeping up
dispersed interstellar gas and dust. Once a critical size is reached
or a nearby supernova explosion occurs a cloud can rain out, that
is collapse, yielding stars and satellites of various sorts. Nowa
word has to be said on the chemistry of cloud complexes. Research
on giant interstellar clouds by means of astrospectrographs and
radio telescopes was initiated in 1963 by a team of the Massachusetts
Institute of Technology and the Lincoln Laboratory. The most crucial
finding was the observation that cloud complexes contained in addition
to Hl a variety of molecules. By including all isotopic species,
close to lOO different types of molecules were recognized. A molecule
of particular relevance is car bon monoxide because its radiation
properties at low temperatures make the molecules an excellent signpost
for the mapping of cloud complexes. However, the most dominant molecule
is hydrogen, in a concentration of about 104 H 1 per cm3. This value
represents ca. 99% of the mass of a giant molecular cloud. The remainder
of the molecules are just "impurities", but considering the size
of a cloud, they can pile up to a rather substantial stack of matter.
For instance, trace constituents such as carbon monoxide, water,
methane, formaldehyde, methyl alcohol, ethyl alcohol, hydrogen cyanide,
ammonia, or the hydroxyl radical far exceed all the mass contained
in our solar system. Ethyl alcohol by itself could readily fill
up the whole Earth with 100-proof "whiskey." In a cloud complex
all carbon is molecularly bound, that is, no atomic carbon remains.
For oxygen, 30% has entered a complex organic molecule. For nitrogen
and sulfur compounds present in the interstellar medium, the data
bank is not sufficient to make a tentative assignment as yet, As
far as the "dust" goes which represents about 1% of the total matter,
we are essentially dealing with ordinary minerals, < 0,5 micron
in size, such as Fe-Mg silicates, native iron, and graphite the
same stuff earth is principally made of. The presence of solid particles
has numerous consequences for the synthesis and protection of organic
molecules in the environment of space. For example, the probability
of collision between atoms and molecules is enhanced, and three-body
reactions become feasible. Moreover, mineral surfaces may provide
not only a convenient "resting place" for certain atoms and molecules,
but by virtue of their crystalline order, catalysis and epitaxis
may ensue. The generation of more complex molecules such as sugars,
amino acids, or the bases of the purines and pyrimidines is conceivable,
but their detection requires more sophisticated technologies. In
brief, the chemistry of giant molecular cloud complexes is basically
one of hydrogen, oxygen, carbon and nitrogen, judged by the prevalence
of molecules containing C-O-H-N. It is noteworthy that in the presence
of a mineral catalyst, simple organic molecules such as formaldehyde
or hydrogen cyanide are expected to yield biochemically interesting
monomers, for instance, sugars, amino acids, purines, and pyrimidines.
Laboratory experiments done under low-temperature conditions have
indeed shown the feasibility of a rapid synthesis of these compounds.
In Fig. 2, the steps involved in the synthesis of common sugars
in a formaldehyde-clay system are schematically shown. All of this
can be used as

Fig.2.a Possible sequences for kaolinite-catalyzed reactions,
b Addition of one unit of formaldehyde at a time to D-glyceraldehydc
in the presence ofkaolinite would result in thc distribution of
the sugars illustratcd. Thermodynamic factors, such as steric repulsions
of hydroxyl groups. play an important role in the distribution of
sugars

Fig.3a-l.Diagram showing major steps in the evolution
of the solar system (from upper left to lower right)'
a Whirlpool galaxy. similar to Milky Way. about 100000 light years
in diameter; frontal and edge-on views
b Contours of a giant molecular cloud complex. a few light years
in diameter revealed by the radiation of carbon monoxide at 2.7
mm 13CO radio line.
c Collapse of molecular cloud complex possibly triggered by supernova
event.
d Rotating solar nebula in statu nascendi with the proto-Sun evolving
in its center.
e Formation of accretion disk; arrows indicate motion of gas.
f Aggregation of particles along midplane of accretion disk.
g and h Accretion from dust, to planetesimals, to planets.
i Retention of primordial atmosphere by a large planet (e.g. Jupiter)
j T Tauri phase, sweeping off "excess" primordial gases from the
solar system leaving atmosphere-free terrestrial planets behind,
k Spacing of the orbits of the planets (astrological symbols) and
the asteroids (dotted area).
I Oort's cloud (comet reservoir) surrounding the Sun with a radius
of about 1 light year in relation to the nearest stars

Fig. 4. Accretion disk across solar system from Mercury
to Neptune. Variations in temperature and oxidation states in the
assumed growth regions or meteorites and cometary bodies

Fig. 5. Diagram showing planetesimals to planets. Feeding
zones widen with time in accordance with the growth rate of the
protoplanet, eventually yielding overlap of zones. Major surviving
feeding zones give rise to planets and asteroids which are displayed
at the square root or distance from the Sun. Planetesimals ejected
from giant planets yield cometary bodies, which accumulate in the
Oort cloud, from where they become episodically ejected and reenter
the solar system. Bombardment of the terrestrial planets by comets
and asteroids throughout the ages has been omitted for graphical
reasons

indication that a dark molecular cloud is a gigantic ice box for
all sorts of organic molecules just waiting to become defrosted,
processed, and utilized for the construction of a cell, once the
environment turns hospitable to the creation of life. The first
step to achieve this goal is the collapse of a molecular cloud and
to illustrate this I have drawn three diagrams. The first (Fig.
3) shows critical events one by one that have led to the formation
of our solar system. The second (Fig. 4) illustrates the wide range
in temperature and oxidation states that prevailed during the formative
years of the planets. The third (Fig. 5) elucidates the logic behind
the enormous variations in the size of the planets. The situation
revealed in Fig. 5 somehow reminds me of a little boy throwing small
rocks horizontally across a water surface, from where the flat pebbles
bounce off numerous times -high and low till their momentum runs
out. Earth has received a tiny share of all types of incoming debris:
first the hot and highly reduced irons, then the stones, and finally
the icy and oxidized material containing gases, water, organic molecules,
and clay minerals. The last dowry may by viewed as frosting on top
of a cake which in due course led to air, sea, and life. The tripartition
of Earth into core, mantle, and crust is a reflection of the stepwise
accretion of the proto- Earth. Since the last incoming material
our "frosting" is assumed to have formed a layer about 700 km thick
around the globe, there certainly were organic molecules galore
available to trigger life.

C. Crystalline Blueprints

Rock-forming minerals are principally composed of oxygen ions which
have as their main coordination partners silicon, aluminum, iron,
calcium, magnesium, sodium, and potassium ions. Crust and upper
mantle may thus be viewed as an ionic oxysphere. Crystals may contain
charge deficiencies, structural irregularities, lattice defects,
and, in hydrated varieties such as clays, may even develop hydrogen
bonds. To structure our discussion, I will begin with a process
commonly described under the heading "epitaxis," a term derived
from the Greek tassein, meaning to arrange or to organize. The growth
of crystalline material on other crystal surfaces is a well-studied
subject in the field of crystallography. Epitaxis can also proceed
on organic templates with the resultant formation of biominerals
in teeth, bones, or shells. Furthermore, organic polymers can promote
the synthesis of other organic polymers, and the living cell is
vivid proof of that. Finally, mineral surfaces may provide sites
for activation and protection of functional groups displayed by
organic molecules, and may accordingly serve as polymerization matrix.
Thus, one can distinguish between four systems in which one partner
represents the template and the other partner the epitaxial product
(Table 1 ). Epitaxis on solid-state surfaces should be viewed in
relation to catalysis because both processes follow a similar reaction
path. Catalysis represents a process in which a solid-state surface
"tries" to establish a thermodynamically favorable phase transition
structure with the adsorbent. Phase-transition structures emerge
which, when chemically stable, lead to

oriented intergrowth. In contrast, should transition structures
introduce a chemical change of the adsorbent such as polymerization,
hydrogenation, dehydrogenation, etc., we are dealing with catalysis.
Principles of cellular catalysis, as, for example, executed by enzymes,
are identical to those observed in mineral systems. Catalysis constitutes
a flow of epitaxial associations, whereas epitaxis involves a "frozen
in" transition structure provided by a morphological catalyst. With
the help of clay minerals, chemical synthesis of a number of physiologically
interesting polymers has been successful; this particularly concerns
the formation of peptides. The mechanism involves carboxyl activation
and the inactivation of functional groups not participating in the
formation of the amide bond by so-called protective groups displayed
along mineral surfaces. The relationships for a kaolinite-amino
acid system are schematically illustrated in Fig. 6. In the presence
of kaolinite, amino acids will be picked up from an aqueous solvent
and brought into solid solution, Amino groups become hydrogen bonded
to structural oxygen, or in the case of basic amino acids, occur
as positive ions. They are tightly fixed to the silicate surface,
and thus rendered inactive. Carboxyl groups associated with charged
Al-oxy-hydroxy groups by means of ionic bridges become directly
attached to the aluminum. In water, amino acids cannot polymerize
because of dipole-dipole interactions. In solid solution, however,
amino acids will polymerize, because the solvent medium does not
interfere, and because

Fig. 6. Polymerization of amino acids along clay templates

this reaction step is favored energetically. In the kaolinite experiment,
about 1000 times more amino acids were polymerized to peptides than
could conceivably become adsorbed to the clay surface. In consequence,
a flow of freshly polymerized molecules across the catalytically
effective mineral surface has to be postulated. Kaolinite is also
instrumental in preferentially synthesizing pentoses and hexoses
from formaldehyde and transforming them into polysaccharides. Kaolinite
can also generate fatty acids and entertain esterification reactions
leading to glycerides. Furthermore, addition of calcium phosphate
to an aqucous mixture of kaolinite, glycerol, and palmitic acids
may yield phospholipid monolayers which are deposited in epitaxial
order with a 40 A periodicity on the crystal surface of kaolinite
as ascertained by transmission electron microscopy. In essence,
all principal building blocks of life have been synthesized by employing
a variety of crystalline blueprints. A remarkable characteristic
of life is that all peptides and proteins are exclusively composed
of the L-optical isomers of amino acids. Preferential polymerization
of L-amino acids on kaolinite can be attributed to the inherent
enantiomorphism of the edges of the octahedral layer of kaolinite
(Fig. 7), and to the fact that kaolinite crystals are either entirely
righthanded or entirely left-handed. Quite a number of ordinary
minerals exhibit chirality. The fact that common carbohydrates such
as cellulose, starch, or cane and beet sugars (sacrose) arc composcd

Fig. 7 a, b. Schematic representation of the edge of a
kaolinite crystal of ideal composition (a),
and its mirror image (b) viewed along the a-axis

of D-configurated monomers can also be related to the optical activity
of the archaic mineral matrix. The structural shape of biomolecules,
which is a key element of cellular function, is asymmetric. It is
conceivable that on the prebiotic Earth left- and righthanded polymers
were generated by mineral printing machines having either D or L
block letters. Once the first organism had chosen the L-configurated
amino acid polymer, or the D-configurated sugar polymer, their mirror
images had no chance to evolve further. Summing up, crystalline
blueprints are effective devices for generating leading biomolecules
and for promoting chirality. Clays are outstanding in this respect,
but they only deliver semifinished products, not life itself.

D. Towards the First Living Cell

Considering the complexity of life it may come as a surprise that
only about 300 monomeric building blocks, lots of water, and some
salt are needed to generate a]] the vital stuff in the genetic and
meta bolic apparatus. However, this stuff has to become neatly packaged
into a cellular envelope in a manner able to fire the engine of
life. So it seems that the most critical question has to do with
the way membranes arise and of how that system is energized and
autocatalytically maintained (evolution is hereby of no relevance
because thermodynamically it constitutes just a disorder phenomenon).
The answer is simple, life has adopted biophosphates for various
structural and functional assignments. In the biological sciences
a quiet revolution is presently going on, namely the recognition
that the architectural principles observed in biophosphates are
identical to those established in the inorganic phosphates. The
early adoption of the name phosphorus, the carrier of light, has
not lost its true meaning over the centuries. Phosphorus, in the
form of phosphate bonds, is the carrier of energy in the living
system. It is the "energy currency" as George Wald so nicely put
it, which becomes printed, exchanged, and converted at various rates
in the perpetuating cycle of life. It is phosphorus which controls
the structure and shape of cellular material and which thus selects
the energy transfer sites. Thus, in the element phosphorus lies
the answer to the question of what distinguishes life from an ordinary
mineral. Life is based on PO 4 units, and rock-forming minerals
on SiO4 units:

It is essentially the pi-electron the high energy bond - in PO4 which maintains the animated world. Since the 7t bond can lie "parallel" to any of the four sigma bonds, giving rise to a variety of differently shaped tetrahedra, a flexible and dynamic tetrahedra network can be created. It is principally the type of metal ion adopted by PO4 that shapes the tetrahedron. In contrast, the SiO4 unit has "just" four sigma bonds which only per

mit the establishmcnt of rigid networks, How can we possibly imagine such networks to look alike? To overcome difficulties in visualizing order phenomena, for instance, in biological membranes, examples of known layered phosphate structures in ordinary minerals are presented for illustration (Fig, 8). Phosphate tetrahedra and metal ion oxygen polyhedra can combine to a variety of geometries including undulating surfaces or concave/convex perforated surfaces, These loosely arranged space fabrics exhibit selective molecular sieve properties and ion exchange characteristics,
Phospholipid membranes are expected to exhibit identical properties and structures as they exist in inorganic phosphate
crystals, even including holes and surface granularities, It is proposed that the interchangeable nature of metal ions causes membranes to act as dynamic molecular sieves, Their pore size and shape must be quite variable as a function of type and availability of metal ions which in the last instances are enzyme controlled, Assuming adenosine triphosphate (ATP) is capable of trapping metal ions but adenosine diphosphate (ADP) is not, a periodic pulsation of the membrane lattice is the consequence,
What we learned in this brief discussion on the structural and functional relationship between inorganic and biotic phosphate "membranes" may now permit us to understand better the mechanisms behind the origin of cellular structures at the dawn of time. It all has to do with the ability of phospholipids to jointly with metal ions construct stable fabrics and become separated from the aqueous medium. Experimental data on emulsions and foams show that micelles equipped with anisotropic membranes are able to grow at the expense of other micelles by consuming them through surface attachment (lowering in surface energy) in a process called emulsification. These globules, soaps, or emulsions as they are termed exhibit an optimal critical diameter in the order of 103 to 104 A. The main feature of this water-organic system is an anisotropic and charged phase boundary layer. The newly generated macromicelles created in a process termed coacervation, will envelop water droplets, whereby the original micelle content is exchanged but according to laws different from those established in aqueous systems. That is, condensation of lipid membranes towards a rigid membrane is achieved by the uptake, for instance, of cholesterol or metal ions. The expulsion of water proceeds during intercellular attachment by means of oxygencoordinated metal bridges. Due to the ionic fabric closely attached to the coacervate, dissolved organic molecules such as peptides or carbohydrates are bonded and precipitated on the membrane surface. In the course of coacervate development structures will arise which are enclosed by a double phospholipid skin (bilayer membrane). Phosphate groups become orientcd towards the aqueous phase and double layers may combine to multilayered stacks. Membrane pouches come into existence, resulting in the for mation of multichambered coacervates
bearing striking resemblance to mitochondria. Judged by the conservative nature of mitochondria, it appears that, as a system, it still carries relics of its abiotic origin. The development of such a selfcontrolled reaction agrees with the thermodynamics of system behavior. A stable cyclic process can exist in the vicinity of a stationary phase and may operate
repeatedly an infinite number of times without ever passing through the stationary phase itself.
In conclusion, the primordial metabolism of the coacervate was in all probability maintained by means of a reversible phosphorylation cycle. In consequence, the origin of metabolism is in no way linked to the development of the genetic transcription apparatus. It must be considered an independent formation process. For this reason the abiotic origin of phosphorylation must be regarded as an equally important step towards the creation of the primordial cell. The problem, therefore, centers around the question of how to polymerize the common monophosphates into di-, tri-, or tetraphosphates, since polyphosphates are unstable in natural environments. The only reasonable choice left is to place the polymerization event within the coacervales. It is conceivable that phospholipid solid-state surfaces served in this capacity, because inorganic mineral surfaces too act as templates and furthermore may catalyze phosphorylation as has been demonstrated for apatite crystals.
The establishment of an interconnected and chemical reaction pattern for the coacervate system as a whole exists when phosphorylation can be maintained. This requires a constant supply of organic molecules and metal ions that are consumed, or utilized during this development. In this manner, a certain modus vivendi is established. Sources of energy were oxidizable organic compounds in the ambience. Molecules such as amino acids or sugars must have been present in huge quantities in the environment in view of their mineral fabricated origin.
So far, however, no vital power was involved. It is postulated that a primitive heterotrophic metabolism improved progressively. Its development took shape independently of the evolution of the nucleic acids and the genetic code. By superimposing the two separately developed entities, (a) the genetic apparatus, and (b) the heterotrophic metabolism, the primordial cell came into existence.

Fig. 9.Composite evolutionary tree (schematic) summarizing
the principal steps in chemical and biological evolution. The sequence
of events depicted for chemical evolution follows from the discussion
in the text. The upward progression from anaerobic to facultative
to acrobic forms is indicated in the shading pattern. Mitochondrial
and chloroplast invasions are roughly drawn between points of suggested
origin and uptake, respectively

The primitive metabolism of coacervates was kept "alive" via phosphorylation
processes and became embodied by the self-reproducing cycles. It
is likely that the nucleic acids were able to encode polypeptides
utilizing certain metal ions. Alternately, nucleic acids succeeded
in adopting the available metalloproteins in their environs among
which must have been enzymes in the billions for their own reproduction.
In any event, the link between the two independently developed events,
(a) the primitive metabolism, and (b) the genetic reproduction apparatus
is represented by the peptides. They are the essential tool by which
coacervate metabolism -for the purpose of nucleic acid replication
was utilized. The structure of phospholipid membranes and the genetic
code are archaic elements -biochemists generally use the term "universal
elements" which remained steadfast in the course of evolution. In
Fig. 9, the three modes of life leading to the first living cell,
the progenote, are schematically depicted. The compost of life started
to form in dark molecular clouds. Once on Earth, the metabolic,
enzymic, and genetic lines took shape, and progressed independently

Fig. 10.Biochemical evolution starting from a common
ancestral state. the progenote (highly schematic)

to eventually merge into the progenote. The subsequent evolution
based on protein and nucleic acid sequence data, has been constructed
in the form of a composite ""evolutionary tree" thus linking the
eukaryotes directly to one kingdom of the prokaryotes, the true
bacteria or eubacteria. Although it is tempting to use such a tree
in order to draw conclusions with respect to the sequence of events
such as the start of (a) photosystem I, (b) photo system II, (e)
respiration, (d) sulfate reduction, etc., recent work using the
16 S ribosomal RNA sequence suggests a different scenario. Data
Indicate that three lines of descent diverged before the level of
complexity usually associated with the prokaryotic cell was reached,
that is: archaebacteria, eubacteria, and "ur'eukaryotes. All three
lineages were independently derived from a common progenote (Fig.
10).

E. Final Comment

We have come a long way during this presentation. I have "crudely"
abstracted from the wealth of data available on the origin of the
first living cell, but still hope that my ""nutshell" approach has
provided at least some idea of the work being done in a field of
science involved with unraveling the mysteries of life. A more comprehensive
treatise may be consulted (Degens 1989) for special references or
to obtain further details on the roots and evolution of the biological
cell in the course of more than 4 billion years of Earth's history.